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Introduction

Hey guys/gals I'm Raymod and finished last season as a Gold 3 adc/support and have some friends joining the fight on the summoner's rift so I wanted to create an in-depth guide full of all my knowledge I feel is a must to know.
Any constructive feedback is welcomed and if you have a problem with the guide then you are more then welcome to find another since I didn't create the guide for you.

Champion Stats

Lets get an understanding on how all the stats work in league so that way you can independently decide which items, runes and masteries to do with your specific lane fight and game.

Attack:

Attack Damage:

Attack damage(AD) is the amount your auto-attacks(AA) do before defenses apply (If you have a total of 200 AD then your AA will do 200 physical damage to the target if they have no armour).
This also applies to items/spells that either state it or have a orange bracket in the details (246) which will be a scaled version of your total AD but you can find out how it scales on websites like this.

Critical Strike:

A critical strike can only happen from auto-attacks unless stated in the ability, a critical strike applies double current attack damage unless you have increased your critical strike damage with something like a infinity edge which will make your critical strikes apply 250% AD. (If you have 200 AD and you land a crit with a infinity edge then you will land a 500 physical damage auto-attack)

Attack Speed(AS):

There is no point in doing lots of damage with your auto-attacks if you cannot do many of them during a fight, this is where you have to make a nice balance. The stat figure is the amount of auto-attacks per second so if you have a 0.65 AS then you will auto-attack .65 times per second (or 1.3 times per 2 seconds or 2 times per 3 seconds) and with 200 AD then you will be doing (/*going by 3 seconds*/ 2AAx200AD=400dp3s=133dps) 133dps. Whereas if you purchased a recurve bow it will increase that AS to about 0.92 so you would be almost doing 200dps.
Also take into account spells that damage are increased by your total AD or the enemy are not allowing you to get off more then one auto-attack before attacking you then it would be recommended to not stress about AS till later.
`2.5AS cap`

Life Steal:

Life steal is a stat that returns health to you for all physical damage dealt from your auto attacks. If you are dealing 200 physical damage from your AA and have 30% lifesteal then each of your AA will grant you 60hp.
`really good for sustaining in lane/jungle`

Armour Penetration:

This bypasses 1:1 armour that your target has if your target has 400armour and you have 40%armour penetration then when you auto-attack them you will negate 160armour leaving them with 240armour to defend against your damage.

Magic:

Ability Power:
Ability Power is a stat used to amplify your champions abilities when they indicate that they can be with a (number) inside of the details.

Cooldown Reduction:
This reduces the cooldown on your champions spells, up to 40%. So if you have a spell with a 100second cooldown on your ultimate and you cap your cdr to 40% then it will be off cd every 60seconds. This is good for using big cd spells during long teamfights or if the enemy is very good at dodging your spells or if you use them as get away spells.

Mana:
Mana is the life source of most champions abilities, if you run out then you cannot cast a spell. Only really something to look at if you play a mage that relies on using abilities for everything.

Mana Regeneration:
This is the rate that you regain mana, this is good for sustaining in lane.

Magic Penetration:
This stat works like armour penetration (above) except it is against magic resist.

Defense:

Health:
If you run out of this you die (just thought you should know), now it when it comes to applying more of this stat onto the champ that you are playing there are things that you need to take into consideration before hand. How well does the champion you have scale with health/healthregen? if your champion has natural armour and magic resist of spells the boost them then health is always good. Secondly, does their team have a true damage champion (vayne, olaf, ahri)? if so then health is better then AR/MR.

Armour:
For every 1 armour that you apply to your champion it grants them 1% more effective maximum health against Physical Damage. So if you have 1000hp and 60AR then it will require 1600physical damage to kill you. It is always recommended to create a balance between both Armour and Health. But if you are versing a team that the only fed champions are AD based then you should purchase a heap of armour.

Magic Resist:
This works exactly the same as Armour expect to do with Magic Damage.

Tenacity:
This stat reduces the effectiveness and duration of CC (crowd control (slows, stuns, snares, silences, taunts, etc.)). This stat is great against wombo combo team comps like malph/amumu or perma slow comps.

Health Regeneration:
Health regen is more of a stat for tanks (adcs use lifesteal) and is great when you have lots of health or are last hitting in top lane because their laner is bullying or having a jungler present a lot. Great on health champs like Dr.mundo or Volibear.

Other:

Gold Income:
A gold income stat is how much gold per 10 seconds you generate. This stat leaves you vulnerable but can grant item spikes faster, best used on passive farmers and supports.

Move Speed:
This applies to the speed you are able to walk around. Best to stack this to keep on champs, get away from champs, be able to get to objectives. There really isnt a massive combat stat in this besides getting to and from things faster.

Roles

Attack Damage Carry (ADC):
This role is filled by a class called marksman, they are the auto-attack class that are designed to kill the enemy teams front line and be the best weapon against tanks and objectives (towers, dragons).
They are very susceptible to cc and dying when played by them self though, so they are a high risk high reward champ.

Support:
A Support is usually the adcs carry, they usually provide crowd control against the enemy adc, heals/buffs your your adc, vision around dragon pit and the bottom side of the map and well judged decision making (when you go in, when to back out, when to leave lane)

Mid:
The middle lane is a very short lane, so for you to get a kill you have to have a champion that can blow someone up in one rotation of your spells. Mid lane is best suited for mages and assassins not only because of the burst they have, but dragon is usually an early game contested objective, so with an adc and support down bot for sustain fight, cc and vision, you need someone that can blow up the enemy back line.

Top Laner:
The top lane is usually called the island, it is far away from the rest of the game and the only objectives are towers and killing people. It's usually played by a bruiser, someone that can fight 1v1 with sustain, tanky stats and some damage. Most top laners take teleport because the top lane usually consists of just farming until a fight breaks out mid/bottom and with teleport they can join the fight.

Jungle:
Jungler is very important and has a variety of strategies, the reason why a jungler was invented was because the way to win fights is to have better items/outplay the enemy team. Items are purchased though in-game gold and there is gold in the jungle in the 'neutral camps' so it's best to utilize all gold on the map.
A jungler is usually in the fog of war farming and is able to run into a lane and 'gank' that lane trying to make it like a 3v2 and surprise the enemy from a bush and then winning that lane.
It's an unwritten law that dragon and baron are their responsibility and must keep vision on those objectives.
*If you have a laner that is being bullied, camp that lane not to get kills but to get their enemy on their toes and play safer.

Game Objectives

Towers:
Destroy the towers and push to the nexus, but there are things that should be known.
Turrets focus in this order:

Outer and Inner towers have 2000hp do 150AD damage and have 100AR/100MR with 0.83AS, if there is no enemy minions it gains an additional 150AR/MR. The inner towers have a 200hp shield which is ignored by minions and grant nearby champions a shield of 30hp per 1.5 seconds to a max of 300hp. The shield regenerates if the tower has not been damaged within 30 seconds.
Outer towers grant 125 global gold and 150 to nearby enemy champions when destroyed and inner towers grant 150 global gold and 100 to nearby enemy minions when destroyed.
If a enemy champion does damage to a champion then it will attack the first champion to do damage.
Your damage to a tower will be your base attack damage plus 40% of your highest bonus stat.

Inhibitor towers have 4.0 attack speed, ignores 82.5% of the targets armour reduces the targets damage dealt by 15%, reduces the targets movement speed by 10%, increases damage by 25% per second up to 125% while focusing one target and when out of combat regenerates 5 health per 5 seconds.

Killing the dragon grants the following buffs when slain the amount of times:
Dragon's Might: +6% Attack Damage and Ability Power
Dragon's Wrath: +15% damage to towers and buildings
Dragon's Flight: +5% movement speed
Dragon's Dominance: +15% damage to minions and monsters
Aspect of the Dragon: Doubles all previous bonuses and your attacks burn for 150 true damage over 5 seconds. only lasts 180 seconds.
Baron:
baron is a largely contested objective in the game because of the stats that it grants for your team.
Baron Nashors stats are: